In conventional visual display devices a pixel corresponds to a LED, LCD or other small component which emits light, either directly or indirectly. These will usually emit light in a broad spread of directions. The intensity of emitted light typically peaks in the straight ahead, or normal direction and gradually falls off as the angle moves away from the straight ahead direction. Typically, the light intensity is within 75% of its straight ahead direction over a range of ±25 degrees.
This spread of ray directions, whilst useful for giving a large field of viewing directions, is undesirable in cases where the viewing distance of the display is outside the uncorrected visual range of the user.
FIG. 1 illustrates an example 100 of a presbyopic user where a display 102 is closer than the user's uncorrected near point. In this example, the distance 103 between the eye and the display is about 300 mm. This will result in a blurred image for the user as the refractive power of their eye 104 is insufficient to sharply focus the image of a pixel on their retina 106. Light from pixel P 108 on the display 102 is emitted in a spread of directions and impinges upon the front surface 110 of the eye 104 of the user within the pupil aperture of about 4 mm diameter, for example. If the display 102 is closer than the visual near point of the user, then the user's eyes cannot refract the light sufficiently, and blurring will occur, which is indicated by blur spot 112 as opposed to a single point on retina 112.
Of course, the user can always wear spectacles, contact lenses or other personal refractive correction solutions; however, this may not always be convenient.
Any discussion of documents, acts, materials, devices, articles or the like which has been included in the present specification is not to be taken as an admission that any or all of these matters form part of the prior art base or were common general knowledge in the field relevant to the present disclosure as it existed before the priority date of each claim of this application.
Throughout this specification the word “comprise”, or variations such as “comprises” or “comprising”, will be understood to imply the inclusion of a stated element, integer or step, or group of elements, integers or steps, but not the exclusion of any other element, integer or step, or group of elements, integers or steps.